Electronic tube of the travelling wave type



June 7, 1960 ca. GUILBAUD E 2,939,997

ELECTRONIC TUBE OF THE TRAVELLING WAVE TYPE Filed Feb. 5, 1957 IIVVf/Vl'O/RS GEORGES Gl/ILBAUD FIG.2

ANDRE .D UB0 /5 By 92//; Q.

nzrae/vaf 2,939,997. Patented June 7,1960;

ELECTRONIC TUBE F THETRAVELLING, WAVE TYPE Georges Guilbaud and Andr Dubois, Paris, France, as-

signors to Compagnie Generals de Telegraphic Sans.

The present invention relates to travelling-wave tubes and more particularly to tubes of the type having crossed electric and magnetic fields.

Tubes of this kind, often referred to as M-type tubes, generally comprise two essentially parallel electrodes consisting of a delay line parallelto an electrode known as a sole, with an electric field being established between these two electrodes by applying to the delay line a positive potential with respect to the sole. The space between the delay line and the sole is additionally subjected to a magnetic field essentially perpendicular to the electric field. In the absence of the high frequency field,

an electron beam directed intothis space between the two electrodes will pass therethrough, parallel to the delay line and perpendicular to the crossed electric and magnetic fields. On the other hand, it is also known that in the presence of such ahigh frequency field, the electrons of the beam propagating inside the space between the electrodes are progressively picked up by the delay line, i.e., little by little are absorbed by the delay lines as the beam of electrons propagates in the space along the two electrodes and the electrons impinge on the delay line structure thereby producing heat therein.

In the known tubes of this type, this beam is generally supplied by a single electron gun, a single collector being disposed at the end of the path followed by theelectrons.

It is known that the output from such a tube is limited,

mainly on account of the difiiculties experienced with the problem of adequately cooling the delay line heated by the impact of the incoming electrons.

Under these circumstances, theonly way of obtaining an output exceeding that which may normally be supplied by a given tube, is-tomake use of several tubes connected in parallel. However, it is known that the control of phase coincidence in a plurality. oftubes of the type mentioned involves considerable difiiculties. In other words, it is extremely difiic'ult in practiceto. realize the exact cophasal relationship of several electrorrbeams operating in parallel in a single tube.

Ithas already been proposed heretofore to. dispose along a single delay line a plurality of spaced cathodes, in order to achieve a more uniform distribution of the interaction along the delay line, and thus to make better use thereof. However, such a solution will cause the beam from one cathode to pass over the adjacent cathode, so that the two beams are thereby mutually coupled, and may interfere with each other and thereby trouble the operation of the tube.

Accordingly, it is an object of the-present invention to avoid all of these diiiiculties anddisadvantages of the prior art. i

It is another object of the presentinvent'ion to provide a travelling wave tube capable of higher outputs than heretofore attainable with a tube of a given physical dimension. A still further object of the present 'invention resid'es in the provision of an electron tube of the travelling wave ellingwave type in which two or more beams of elec-.

trons are propagated without any. interaction with each, other.

A further object of the present invention is to increase the output of an electron tube of the travelling wave type byprovidiugtwo or more electron beams operativein series with respect to each other and with respect to a single delay line so as to avoid any difiiculties with. pro: viding cophasal relationship of the energy producedbythe interactionof the beams by the delay lines. Stillanother object of-the present invention resides in the construction of an electron tube of a travelling wave amplifier in] which the problem involved in adequate. cooling of a tube of a given size Wuhan increase in the output thereof is solved in an advantageous manner...

These and further'objects, features and advantages v.of the present invention will become more obvious from the following description when taken in connection with the. accompanying drawing which shows, for purposes 1 of illustration only, one embodimentinaccordance withthe present invention, and wherein:

Figure 1-is.a cross sectionalviewof a-tube according to the present invention, taken along line 1'-1 of Figure 2, and

Figure 2 is a cross sectional view taken along line 2-2 of 'Figure- 1.

The present invention provides a travelling-wave tube; with 'crossed'electricand magnetic fields, comprising at least two sourcesof electronsloeated 'and disposed so as to radiateoremit two beains which, on the one-.han'd are mutually uncoupled-with respect 'to each other, and onthe otherhand, are each coupled with the single delay line. 'Iliisiuncoupling is-obtain'ed' by providing between two adjacent cathodes an intermediate collector carried ator adju'stedt'o' the samepotentia'l that of the delay line,- preferably'- also flush with the sole insuch a-manner that the propagation of the wave in the delay line is-not, interfered 'withthereby.

Referring now more particularly -to Figures land- 2 wherein like reference numerals are used in the various views to designate like parts, the -tube illustrated therein is'a backward travelling-wave oscillator, of circular struc-- ture, known as an M-type carcinotron tube. The tube comprises an evacuated cylindrical envelope-.1, containing two electrodes consisting of a delay line l coaxial with the envelope 1 onto which it is secured, and of-a circular sole 3 supportedbyinsulating pins-or sleeves 4-. The delay line zwhich may be of any suitable construction is coupled at one end thereof to air-output 5, and the opposite end thereof is coated with anattenuating material 6-of suitable choice. A voltage source 7 witlt'a plurality of adjustable-taps supplies the necessary Volt ages, onset the taps, by meansof connection 22 pro ducinga radially directed electric field between elee trodes 2 and 3, electrode 2 being grounded, as isalso envelope 1 and the positive side ofvoltage source-7'. Furthermore, the polar pieces '8' (Figure'Z) of-any--'suitable magnet establish a magnetic field, directed along the axis of the tube. It is to be noted that the tube structure so far described aboven's well known per-se.

According toxthe present invention, the tube illustrated herein includes a first electron gun 9 and a first collector 1%." Gun 9is of a wellknownconventional-typeaud -is disposed, as is known with. the Carcino'tron tubes, at the end 'of the delay lines 2, adjacent output 5.1.The electron gun 9 includes a cathode 16, located in a s lotr'or recess providedin thefocusingrplate 15; and-a focusing plate 17, both plates being substantially parallel to the cratesas follows: beam 25 same, conditions, along that portion positioned ,beyondcollector10, and

emitted which have not;

of the delay line :2 in'the course of travelthereof; are

line 2'=and sole 3. The inner space 18 of the electron gun 9 thus constitutes essentially an extension of the space bounded by delay line 2 and sole 3. Plate 17 is biased by connection 23 and plate by connection ,24. Collector 10 is secured between the wallsof envelope,

1, inside-a slot or recess providedjinjsole 3, and is brought to or placed 'at the suitable connections therewith (not shown); 'Itisplaced flush with sole, 3' so as not to Ztrouble. for disturb the propagation of the'high frequency wave in thedelay li'ne 2. Eventually thecollector 10 may.,also besur'fa'cetreated by any known means, so as to avoid any secondary emission therefrom;

'The tube according to the presentinvention addition ally include a second electron gun 11 anda, secon collector 12." Gun 11 is located directly, behind colle'ctor'10in the direction of propagation of theelectron beam, andis identicaljv'vith,gun"9,1thev electrodes ,15', 16', 171.118; thereof corresponding operatively to electrodes '15-, '16, 17, $18 of gun 9., The innerspace of electron gun 11, however, is slanted or inclinedwith respect to the mean pathvof the electrodes, 'in order to take intovaccount the disturbing elfect of collector 10' on the electric field and thereby essentially compensate for the same; The various electrodes of electron gun 11 are at thev same potential 'as those of electron gun 9, cathode '16 of gun :11, however, being provided with a bias connection 19 independent from connection 20 of cathode 16 of gun 9, so that these two cathodes 16" and 16 might be adjusted to d-ifiierent potentials, if so desired.

' r Operation The tube in accordance with the present invention opemitted from gun 9 propagates through the spacebetween electrodes 2 and 3,

potential of'delayline 2 by.

, opposite to, that of 15' designatedby-reference numeral 5 in Figure 1 is used as input while an output coupling is provided serving as output coupling which may be constructed similar to the coupling 5 and which is located at the end of the delay line opposite to that of the coupling 5. If used as amplifier,v the' attenuating means with. 1

Moreover, the present applicationis not limited to the particular showing of. the attenuating means 6 but may use any other suitable external attenuating means. For: example,- if the tube is to be used as oscillator then the "coupling normally used in connection with operation thereof as amplifier which is located at the end thereof:

with an external attenuating meansin which all energy flowing in-the vdirection of the travel of the electron beams and 2 6tis dissipated.

' a 'We claim:

1. In. an .electron tube of the travelling wave type, the combinationcomprising two electrodes defining therebetween a space, one of saidjelectrodesbeinga" delay respect to the direction across: the crossed electric and magneitc fields, and then I through the'region ,of collector 10,,where no electric field exists due to the same potentialwhich' is appliedto both the.,delay line Z-and collector 10.-. The electrons which havenotbeen, collected or absorbedby the delay line-2 during the propagation, along the, delay line) are then deflected by the magnetic field toward collector. 10,- so that beam 25,is. entirely captured and removed before ever reaching gun 11.

Beam 26, emitted by gun of the delay line 2 been, picked up ,bythat-portion It is to beunderstood that the present inventionis not limited to the specific embodiment described herein given only by way of'exampla'but is capable of many changes and modifications within the spirit of the-present invention and I intend to cover all such changes and modifications as encompassed by'the appended claims, Thus, for example, the present invention is not limited to the use of only two beams but maybe used with more than two beams, whereby more than two beams areoperatively associated with the beamsv being operatively associated in series with respect toeach other along delay'line. 'Moreover, particular'tube illustrated herein, but is" suitable for use with any tube'having crossed electric and magnetic fields whether circular or rectilinear, or whether'oscillators or amplifiers. :yc'ntion are to be used as amplifiers, then the, coupling difierent portions of the. the invention is not limited ,to the line having mutually uncoupled ends, and means for propagating two separate beams of electrons in said space in coupled relationship with said delay line-including means to'preventinteraction between said two beams.

2. In an electron tube the combination according to claim '1 wherein said last-mentioned means includes a collector at the same potential as said'delay line.

3. In an electron tube the combination 'according'to claim 2 wherein said means for propagating beams of electrons includes two electron guns, one of said guns being locatefdbehind said collector in the direct-ion of travel of the electron beams.

4. In an electron tubethe combination according to claim 3 wherein said one electron, gun is inclined-with of, mean travel of said electrons.

5. In an electron-tubeof the travelling wave type, the combination comprising two, electrodes defining therebetween a space, one; fsaid electrodes being a delay line having mutually uncoupled ends, and means for prop'agatingtwo separate beams of electrons seriatim' in 7 including rne'ansifor decoupling said two beams. Y

11,, propd ates: under the;

the electrons thns field caused the same single delay line, i

If .tubes in accordance with :the present in 4 6. "In "an electron tubethe combination according to claim 5 wherein said delay line consists oi a single delay line andwherein' said meansrfor propagating two Scp-.

arate beams of electrons includes'two separate electron guns, and wherein one'of said guns is inclined with re-' spect to the average path of travel of, said beams.

7. In an electron tube the combination according to claim 6 wherein one of said two guns is located near one end of said, delay'lin'e andthe other of said guns is located ataj point intermediate the two ends thereof.

8. In an. electron tube the combination according to claim 1 further comprising at least one coupling means for transferring energy from said delay line to an externalloadLf t t 9. In an electron tube'the combination according to claim 7 wherein said tube is an amplifier and is provided with two coupling means located near the two ends of said delay line. H i

10. In an 'electronitube the combination according to claim 7 wherein said electron tube is an oscillator and is provided with one coupling means near one end of said delay line and with attenuating means operatively connected with the'other, end of said delay line.

11. In-an electron tube of the travelling wave type the combination-according to claim 10 wherein said attenuating means is'applieddirectly to said delay ,line'.

"12. Ina travellingfyvave tubehaving a delayline and a non-delaying electrode parallelithereto, said delay line and, said electrode defining'a space therebetween, means for generatingatransverse electric field betwe'en said line I and said electrode, means for generating a transversemage '6 may be dispensed the coupling 5 may be connected lines of force, at least two electron guns positioned at difierent points with respect to said delay line for emitting beams propagating in said space in coupled relationship with said line, and means for decoupling said two beams.

13. In a travelling wave tube the combination according to claim 12 wherein said decoupling means includes a collector electrode located near one of said points, said collector electrode being insulated from said non-delaying electrode and being at the same potential as said delay line, said collector electrode being adapted to collect one of said electron beams.

14. In a travelling wave tube the combination according to claim 13 wherein said collector electrode is provided with an electron collecting surface flush with said non-delaying electrode and is positioned in a slot provided in said non-delaying electrode.

15. In a travelling wave tube the combination according to claim 12 wherein one of said guns is positioned in tilted relationship with respect to said delay line and nondelaying electrode.

16. A travelling wave tube of the type having crossed fields comprising, within an evacuated envelope, an anode shaped as a delay line, a member having a conductive surface parallel to said anode and bounding therewith an electron and wave interaction space, and a-chain of nonoverlapping systems each of which includes a source of an electron beam propagating in said space and a collector electrode at substantially the same potential as said anode and adapted to absorb substantially all the electrons of the beam, the collector of one system being located close to and preceding the electron beam source of the following system, whereby non-overlapping beams, in-

serial relationship with each other, are caused to propagate in the same direction in said interaction space, substantially the whole space being traversed by electrons of one beam, while each beam traverses a different portion of said space.

17. A travelling wa-ve tube comprising, within an evacuated envelope, an anode shaped as a delay line, a negative electrode parallel to said anode and bounding therewith an electron and wave interaction space, said space being traversed by electrostatic field lines of force between said anode and negative electrode, and a chain of nonoverlapping systems each of which includes a source of an electron beam propagating in said space and a collector electrode having an electron-collecting surface at essentially the same potential as said anode and adapted to absorb substantially all the electrons of the beam, the collector of one system being located within a slot provided in and electrically insulated from said negative electrode close to and preceding the electron beam source of the following system, the electron collecting surfaces of all the collectors disposed in said slots being flush with said negative electrode, whereby non-overlapping beams, in serial relationship with each other, are caused to propagate in the same direction in said interaction space, so that substantially the whole space is traversed by electrons of one beam and each beam traverses a difierent portion of said space, a source of magnetic field being provided to generate magnetic field lines of force through said space substantially perpendicular to said electrostatic field lines of force.

18. A traveling wave tube as claimed in claim 17 wherein at least some of the electrodes are conductor electrodes, and further comprising means for raising all the conductor electrodes to substantially the same potential as said anode. I 5

19. In an electron tube of the travelling wave type, the combination comprising two electrodes defining therebetween a space, one of said electrodes being a delay line having mutually uncoupled ends, and means for propagating two separate beams of electrons in said space in essentially non-overlapping coupled relationship with said delay line.

20. In an electron tube of the travelling wave type, the combination comprising two electrodes defining therebetween a space, one of said electrodes being a delay line having mutually uncoupled ends, and means for propagating two separate beams of electrons in said space in essentially non-overlapping coupled relationship with said delay line, including means to prevent interaction between said two beams.

21. A travelling wave tube of the type having crossed fields including an anode shaped as a delay line, a negative electrode having a conductive surface essentially parallel to said anode and bounding therewith an electron and wave interaction space having two ends, an extreme electron gun and an extreme collector electrode located at said two ends respectively, at least one intermediate electron gun and collector electrode alternately located near intermediate points of said space so as to divide said space into adjacent portions each having an electron gun at one end and a collector electrode at the other end, each intermediate collector being located close to the next electron gun.

22. A travelling wave tube of the type having crossed fields including an anode shaped as a delay line, a negative electrode having a conductive surface essentially par allel to said anode and bounding therewith an electron and wave interaction space having two ends, an extreme electron gun and an extreme collector electrode located at said two ends respectively, at least one intermediate electron gun and collector electrode alternately located near intermediate points of said space so as to divide said space into adjacent portions each having an electron gun near one end and a collector near the other end, each intermediate collector being located close to the next electron gun, and means for bringing all the collector electrodes to the same potential as said delay line to thereby produce therebetween electrically fieldless spaces for stopping therein the propagation of electrons and assuring absorption thereof in the collectors, whereby non-overlapping beams, in serial relationship with each other, are caused to propagate in the same direction in said interaction space.

23. In an electron tube of the travelling wave type having an interaction space for propagating electrons therein under the action of mutually crossed magnetic and electric fields, the combination comprising two electrode means defining therebetween said interaction space, and cathode means within said tube for emitting electrons adapted to propagate as separate beams of electrons in said interaction space in mutually uncoupled relationship with one another and in coupled relationship with said delay line electrode means.

24. In an electron tube of the travelling wave type in which electrons are propagated in an interaction space under the influence of mutually crossed magnetic and electric fields, comprising a plurality of electrode means defining therebetween said interaction space, one of said electrode means being a delay line, and means within said tube including separate cathode means for propagating a plurality of beams of electrons in said interaction space in coupled relationship with said delay line electrode means and in mutually uncoupled relationship with respect to one another.

References Cited in the file of this patent UNITED STATES PATENTS 2,622,158 Ludi Dec. 16, 1952 2,623,193 Bruck Dec. 23, 1952 2,680,825 Warnecke et a1 June 8, 1954 2,687,777 Warnecke et a1 Aug. 31, 1954 

